Hydraulic method and apparatus for uniform radial compression and catheter mounting of radially expandable intraluminal stents and stented grafts

ABSTRACT

An apparatus for mounting a radially expandable intraluminal stent or stented graft onto a delivery catheter. The apparatus comprises a hollow housing defining an interior chamber and a fluid port which communicates with the interior chamber. Disposed within the interior chamber of the housing is a collapsible, resilient tubular sleeve which is sized to receive a portion of the delivery catheter having the stent or stented graft positioned thereupon. The sleeve includes an open end which communicates with the exterior of the housing. The pressurization of the interior chamber of the housing via the fluid port facilitates the uniform radial compression of the sleeve, with the depressurization of the housing via the fluid port causing the sleeve to resiliently return to an uncompressed state.

This patent application is a division of application Ser. No. 08/816,259filed on Mar. 13, 1997 now U.S. Pat. No. 5,810,838.

FIELD OF THE INVENTION

The present invention pertains generally to medical devices, and moreparticularly to an apparatus and method for mounting a stent or stentedgraft onto a delivery catheter through the use of hydraulics tofacilitate the uniform radial compression of the stent or stented graft.

BACKGROUND OF THE INVENTION

The term "stent" is generally used to describe endoprothstetic medicaldevices which are implanted in anatomical passageways (e.g., bloodvessels, gastrointestinal tract, genitourinary tract, endocrine ducts,etc. . . .) of the body for the purpose of maintaining the patency orstate of dilation of the passageway, reinforcing the passageway, oranchoring a tubular graft or other object within the passageway.

Typically, such stents are implanted in blood vessels to maintaindilation and patency of an occluded region of blood vessel, or to bridgea weakened or aneurysmic region of blood vessel. On the other hand, sometypical non-vascular applications of such stents are for the treatmentof constrictions or injuries to the gastrointestinal tract (e.g.,esophagus), ducts of the biliary tree (e.g., common bile duct) oranatomical passageways of the genitourinary tract (e.g., ureter, urethrafallopian tube, etc.).

Transluminally implantable stents are initially disposed in a compactconfiguration of relatively small diameter, and are initially mountedupon or within a delivery catheter to facilitate insertion andtransluminal advancement of the stent into the desired anatomicalpassageway. Thereafter, such stents are radially expanded to a larger"operative" diameter which is equal to or slightly larger than thediameter of the anatomical passageway in which the stent is to beimplanted. When radially expanded to such operative diameter, the stentwill typically become released or separated from the delivery catheterand anchored or frictionally engaged to the surrounding wall of theanatomical passageway.

Some stents have a pliable, continuous tubular covering, in which casethey are typically referred to as a "stented graft" or "stent-graft".

In general, stents and stented grafts fall into two major categories--a)self-expanding and b) pressure-expandable. Those of the self-expandingvariety may be formed of resilient or shape memory material (e.g.,spring steel or nitinol™) which is capable of self-expanding from itsfirst (radially compact) diameter to its second (operative) diameterwithout the exertion of outwardly-directed force against the stent orstented graft. Examples of such self-expanding stents and stented graftsare set forth in U.S. Pat. Nos. 4,655,771 (Wallsten, et al); 4,954,126(Wallsten); 5,061,275 (Wallsten, et al); 4,580,568 (Gianturco);4,830,003 (Wolf, et al); 5,035,706 (Gianturco, et al); 5,330,400 (Song)and 5,354,308 (Simon, et al) and Foreign Patent Publication Nos.WO94/12136; WO92/06734 and EPA183372. Those of the pressure-expandable(i.e., "passive expandable") variety may be formed of plasticallydeformable material (e.g., stainless steel) which is initially formed inits first (radially compact) diameter and remains stable in such firstdiameter until such time outwardly directed pressure is exerted upon thestent or stented graft to cause radial expansion and resultant plasticdeformation of the stent or stented graft, to its second (operative)diameter. Examples of such pressure-expandable stents and stented graftsare set forth in U.S. Pat. Nos. 5,135,536 (Hillstead); 5,161,547(Tower); 5,292,331 (Boneau); 5,304,200 (Spaulding); 4,733,665 (Palmaz);5,282,823 (Schwartz, et al); 4,776,337 (Palmaz); and 5,403,341 (Solar)and Foreign Patent Publication Nos. EPA480667; and WO95/08966.

In many applications, careful positioning and sound anchoring of thestent or stented graft is critical to the successful treatment of theunderlying medical problem. In this regard, the delivery catheter whichis utilized to insert and position the stent or stented graft may be animportant aspect of the overall system. Various types of deliverycatheters for stents and stented grafts have been previously known,including those described in U.S. Pat. Nos. 4,665,918 (Garza, et al);4,733,665 (Palmaz); 4,739,762 (Palmaz); 4,762,125 (Leiman, et al);,776,337 (Palmaz); 4,838,269 (Robinson, et al); 4,994,071 (MacGregor);5,037,427 (Harada, et al); 5,089,005 (Harada); 5,102,417 (Palmaz);5,108,416 (Ryan, et al); 5,141,498 (Christian); 5,181,920 (Mueller, etal); 5,195,984 (Schatz); 5,201,901 (Harada, et al); 5,269,763 (Boehmer,et al); 5,275,622 (Lazarus, et al); 5,290,295 (Querals, et al);5,306,294 (Winston, et al); 5,318,588 (Horzewski, et al); 5,344,426(Lau, et al); 5,350,363 (Goode, et al); 5,360,401 (Turnland); 5,391,172(Williams, et al); 5,397,345 (Lazarus); 5,405,380 (Gianotti, et al);5,443,452 (Hart, et al); 5,453,090 (Martinez, et al); 5,456,284 (Ryan,et al); and 5,456,694 (Marin, et al) and Foreign Patent Publication Nos.EP-0308-815-A2; EP-0335-341-A1; EP-364-787-A; EP-0442-657-A2;EP-482976-A; EP-0505-686-A1; EP-0611-556-A1; EP-0638-290-A1; WO94/15549;WO95/01761; GB2196-857-A; DE3042-229; and DE3737-121-A.

As previously indicated, many types of stents or stented grafts arecurrently used in relation to the treatment of various disorders.Perhaps the most common use of radially expandable stents and stentedgrafts is in relation to the treatment of narrowed or constricted bloodvessels. For these applications, pressure expandable stents aretypically employed, with the delivery of the stent to the desiredtreatment site being facilitated through the use of a delivery catheterincluding an inflatable balloon which is used to facilitate the radialexpansion of the stent positioned thereupon to its final, operativediameter.

When using pressure expandable stents or stented grafts on a deliverycatheter including an inflatable balloon, the stent or stented graftmust be manually mounted to the balloon of the delivery catheter by thephysician prior to the initiation of the treatment. Such mounting istypically accomplished by the physician manually squeezing orcompressing the stent or stented graft onto the balloon of the deliverycatheter. It is also known in the prior art for delivery catheters to beprovided wherein the stent or stented graft is pre-mounted thereto. Inthis respect, the stent or stented graft is mounted to the deliverycatheter by the manufacturer, and sold as a combined unit.

Though the above-described mounting procedure is often used, a majordrawback associated therewith is that often times the stent or stentedgraft is not uniformly compressed onto the balloon of the deliverycatheter. Indeed, the hand crimping of the stent or stented graft ontothe balloon of the delivery catheter usually results in uneven crimping.Such non-uniform or uneven crimping of the stent or stented graft ontothe balloon in turn results in non-uniform or uneven re-expansion of thestent or stented graft when radially expanded by the inflation of theballoon. If re-expanded in a non-uniform manner, the stent or stentedgraft, though being in contact with the luminal surface of a particularanatomical passageway, will not necessarily exert even pressurethereagainst, which is undesirable due to the increased risk of thestent or stented graft dislodging from its operative position within thetreatment site. Additionally, such non-uniform crimping may causeproblems during the advancement of the delivery catheter through theanatomical passageway to the desired treatment site. Such problemsinclude those portions of the stent or stented graft which are notcompressed against the balloon of the delivery catheter inadvertentlycontacting and damaging the lining of the luminal surface of theanatomical passageway.

In view of the foregoing, it is highly desirable to facilitate theuniform crimping or compression of the stent or stented graft over theballoon of the delivery catheter. The present invention addresses thisneed by providing an apparatus and method which, through the use ofhydraulics, facilitates the uniform radial compression of the stent orstented graft about a portion of the delivery catheter. The presentinvention is used primarily in relation to pressure expandable stents orstented grafts which are mounted to the balloon of a delivery catheter.However, the present invention may also be used in relation toself-expanding stents or stented grafts including a latching mechanismwhich engages when the stent or stented graft is radially compressed.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an apparatusfor mounting a radially expandable intraluminal stent or stented graftonto a delivery catheter. The apparatus comprises a hollow housing whichdefines an interior chamber and a fluid port which communicates with theinterior chamber. Disposed within the interior chamber of the housing isa collapsible, resilient tubular sleeve which is sized to receive aportion of the delivery catheter having the stent or stented graftpositioned thereupon. The sleeve includes an open end which communicateswith the exterior of the housing. In the present apparatus, thepressurization of the interior chamber of the housing via its fluid portfacilitates the uniform radial compression of the elongate sleeve, withthe depressurization of the housing via its fluid port being operationalto allow the sleeve to resiliently return to an uncompressed state. Thecollapse of the sleeve in turn facilitates the uniform radialcompression or crimping of the stent or stented graft therewithin, thusmounting the stent or stented graft onto the delivery catheter.Typically, the present apparatus is used in conjunction with pressureexpandable stents for mounting the same onto the radially expandableballoon of a delivery catheter.

The elongate, tubular sleeve of the present apparatus may be fabricatedfrom polyethylene (PE) having a preferred wall thickness of from about0.001 to 0.003 inches. The sleeve may alternatively be fabricated frompolyethylene terephthalate (PET) having a preferred wall thickness offrom about 0.0001 to 0.001 inches, or from nylon (PEBAX™, Atochimie,Courbevoie, Hauts-Ve-Sine, France) having a preferred wall thickness offrom about 0.001 to 0.003 inches. Additionally, the sleeve may befabricated from an elastomeric material having a preferred wallthickness of approximately 0.005 inches.

In the apparatus constructed in accordance with the present invention,the housing may further comprise a pressure gauge fluidly connected tothe interior chamber for monitoring the pressure level therewithin. Theinterior chamber of the housing is typically pressurized with a fluid,and preferably a liquid for minimum compressibility. However, theinterior chamber may alternatively be pressurized with a gas, though theuse of a gas for the pressurizing medium is less desirable due to itsincreased compressibility as compared to a liquid. The pressurization ofthe interior chamber is typically facilitated by an angioplasty ballooninflation device (e.g., the syringe used to inflate the balloon of thedelivery catheter). In some instances, the angioplasty balloon inflationdevice may include its own pressure gauge, thus eliminating the need forthe optional pressure gauge fluidly connected to the interior chamber ofthe housing. However, those of ordinary skill in the art will recognizethat alternative devices may be used to pressurize the interior chamberof the housing.

Further in accordance with the present invention, there is provided ahydraulic method of mounting a radially expandable intraluminal stent orstented graft onto a delivery catheter. The method comprises the initialstep of providing a crimping apparatus which has the above-describedstructural and functional attributes. Thereafter, a radially expandablestent or stented graft is positioned upon a portion of the deliverycatheter, with that portion of the delivery catheter having the stent orstented graft positioned thereupon then being inserted into the sleevevia the open end thereof. Thereafter, the interior chamber of thehousing is pressurized via the fluid port to facilitate the uniformradial compression of the sleeve and the stent or stented graftpositioned therein about the delivery catheter. The interior chamber ofthe housing is then depressurized via the fluid port, with the portionof the delivery catheter having the stent or stented graft mountedthereto being removed or withdrawn from within the interior of thesleeve.

As previously indicated, the interior chamber of the housing istypically pressurized with a fluid through the use of the syringe orother inflation fluid infusion device used to facilitate the inflationof the balloon of the delivery catheter. Additionally, the stentpositioned upon the delivery catheter will typically comprise a pressureexpandable stent, though self-expanding stents including latchingmechanisms which engage when the stent is collapsed may also be used inconjunction with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings wherein:

FIG. 1 is a perspective view of the mounting apparatus of the presentinvention, illustrating the manner in which a delivery catheter havingan uncompressed stent positioned thereupon is inserted into the mountingapparatus;

FIG. 2 is a cross-sectional view of the mounting apparatus, illustratingthe delivery catheter and uncompressed stent as positioned therein priorto the pressurization of the interior chamber thereof;

FIG. 3 is a cross-sectional view of the mounting apparatus, illustratingthe delivery catheter and radially compressed stent as positionedtherein subsequent to the pressurization of the interior chamberthereof;

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3; and

FIG. 5 is a partial perspective view of the delivery catheter,illustrating the stent as being radially compressed thereon through theuse of the mounting apparatus shown in FIGS. 1-3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein the showings are for purposes ofillustrating a preferred embodiment of the present invention only, andnot for purposes of limiting the same, FIG. 1 perspectively illustratesan apparatus 10 for mounting a radially expandable intraluminal stent 12or stented graft onto a delivery catheter 14. The stent 12 with whichthe apparatus 10 is utilized will typically comprise a pressureexpandable stent, with the stent 12 shown in FIGS. 1-5 being of a typecommonly referred to as a "zig-zag" stent. Additionally, the deliverycatheter 14 upon which the pressure expandable stent 12 is positionedwill typically comprise a balloon delivery catheter having a tubularbody 16 which includes an elongate, inflatable balloon 18 attached tothe outer surface thereof in relative close proximity to its distal end.The stent 12 is mounted to the balloon 18 of the delivery catheter 14 byinitially positioning the stent 12 over the balloon 18, and subsequentlyradially compressing the stent 12 thereabout. The deployment of thecollapsed stent 12 into a desired intraluminal site is facilitated bythe inflation of the balloon 18, which in turn causes the stent 12mounted thereto to be expanded radially outwardly into direct contactwith the luminal surface of an anatomical passageway. As will bedescribed in more detail below, the apparatus 10 of the presentinvention is specifically adapted to facilitate the mounting of thestent 12 onto the delivery catheter 14 through the uniform radialcompression of the stent 12 about the balloon 18.

Those of ordinary skill in the art will recognize that the apparatus 10of the present invention may also be used to facilitate the mounting ofother types of pressure expandable stents or stented grafts onto theballoon 18 of the delivery catheter 14. Additionally, the apparatus 10may be used to facilitate the mounting of self-expanding stents orstented grafts onto the balloon 18 of the delivery catheter 14 whereinsuch self-expanding stents or stented grafts include latching mechanismswhich engage when the stent or stented graft is collapsed. Moreover, theapparatus 10 may be used to facilitate the mounting of stents or stentedgrafts onto delivery catheters other than for balloon deliverycatheters. Thus, the particular descriptions of the stent 12 anddelivery catheter 14 set forth herein are for illustrative purposes onlyand are not intended to limit the scope of the present invention.

In the preferred embodiment, the apparatus 10 comprises a hollow,cylindrically configured housing 20 which defines a proximal end 22 anda distal end 24. The distal end 24 of the housing 20 may be enclosed byan end cap 26 which, though not shown, may comprise an integral portionof the housing 20. Disposed within the proximal end 22 of the housing 20is an annular entry member 28 which defines a circularly configuredopening 30 extending axially therethrough. The housing 20, end cap 26and entry member 28, and more particularly the inner surfaces thereof,collectively define an interior chamber 32 of the housing 20.

As best seen in FIGS. 2 and 3, disposed within the interior chamber 32of the housing 20 is a collapsible, resilient tubular sleeve 34 having aproximal end which is attached to the inner surface of the entry member28 and a distal end which is attached to the inner surface of the endcap 26. When attached to the entry member 28, the proximal end of thesleeve 34 circumvents the opening 30, with the inner surface of thesleeve 34 being substantially continuous with the peripheral inner wallof the entry member 28 which defines the opening 30. When attached tothe end cap 26 and entry member 28 in the aforementioned manner, thesleeve 34 extends axially through the interior chamber 32, with theinterior of the sleeve 34 communicating with the exterior of theapparatus 10 via the opening 30 within the entry member 28.

The sleeve 34 of the apparatus 10 may be fabricated from polyethylene(PE) having a preferred wall thickness of from about 0.001 to 0.003inches. The sleeve 34 may alternatively be fabricated from polyethyleneterephthlate (PET) having a preferred wall thickness of from about0.0001 to 0.001 inches, or from nylon (PEBAX™, Atochimie, Courbevoie,Hauts-Ve-Sine France) having a preferred wall thickness of from about0.001 to 0.003 inches. Additionally, the sleeve 34 may be fabricatedfrom an elastomeric material having a preferred wall thickness ofapproximately 0.005 inches. In all embodiments, the sleeve 34 issufficiently resilient to be selectively collapsible and expandable inaccordance with changes in the pressure level within the interiorchamber 32, as will be discussed in more detail below.

As seen in FIGS. 1-3, the apparatus 10 constructed in accordance withthe present invention further comprises a fluid port 36 which isattached to the housing 20 and communicates with the interior chamber 32thereof. Also attached to the housing 20 adjacent the fluid port 36 is apressure gauge 38 which also communicates with the interior chamber 32.

Having thus described the structural components of the apparatus 10, themethod of using the same to facilitate the mounting of the stent 12 uponthe balloon 18 of the delivery catheter 14 will now be described withreference to FIGS. 1-5.

In the present method, the stent 12, while in its uncollapsed state, iscentrally positioned upon the balloon 18 of the delivery catheter 14such that the opposed ends of the balloon 18 protrude from respectiveends of the stent 12. Thereafter, as seen in FIG. 2, the deliverycatheter 14 having the stent 12 positioned upon the balloon 18 isinserted into the interior of sleeve 34 via the opening 30 within theentry member 28. Importantly, the inner diameter of the sleeve 34 issized so as to allow the uncollapsed stent 12 to be easily inserted intothe sleeve 34 without interfering with the inner surface thereof.

Subsequent to the insertion of the delivery catheter 14 and stent 12into the sleeve 34 in the manner shown in FIG. 2, the interior chamber32 of the housing 20 is pressurized via the fluid port 36. Moreparticularly, the interior chamber 32 is pressurized with a fluid, withsuch pressurization typically being facilitated by an angioplastyballoon inflation device (e.g., the syringe used to inflate the balloon18 of the delivery catheter 14). However, those of ordinary skill in theart will recognize that alternative devices may be used to pressurizethe interior chamber 32 of the housing 20. As seen in FIG. 3, due to theresiliency of the sleeve 34, the pressurization of the interior chamber32 in the aforementioned manner facilitates the uniform radialcompression of the sleeve 34 about the stent. 12 positioned therewithin.The application of the uniform radial compressive forces to the stent 12by the sleeve 34 in turn causes the stent 12 to be uniformly radiallycollapsed or compressed about (i.e., mounted to) the balloon 18 of thedelivery catheter 14.

After the stent 12 has been mounted to the balloon 18 of the deliverycatheter 14 in the aforementioned manner, the interior chamber 32 of thehousing 20 is depressurized via the fluid port 36. The resultant returnof the interior chamber 32 to atmospheric pressure causes the sleeve 34to resiliently return to its original, uncompressed configuration asshown in FIG. 2. Thereafter, the delivery catheter 14 having the stent12 mounted thereto is removed from within the sleeve 34 via the opening30, with the stent 12 being tightly collapsed onto the balloon 18 of thedelivery catheter 14 in the manner shown in FIG. 5.

The optional inclusion of the pressure gauge 38 with the apparatus 10provides a visual indication as to whether the pressure level within theinterior chamber 32 is sufficient to facilitate the uniform radialcompression of the sleeve 34 from its uncollapsed state (shown in FIG.2) to its collapsed state (shown in FIG. 3). It will be recognized thatan additional or alternative visual indication of the sleeve 34 movingto its collapsed state may be achieved by fabricating the housing 12from a transparent or translucent material.

Advantageously, the apparatus 10 constructed in accordance with thepresent invention facilitates the uniform crimping or compression of thestent 12 or stented graft over the balloon 18 of the delivery catheter14. Due to such uniform compression, the stent 12 radially expands in auniform manner upon the inflation of the balloon 18 and thus exerts evenpressure against the luminal surface of the anatomical passageway whenplaced into direct contact wherewith. As such, the stent 12, when in itsoperative position within the anatomical passageway, is less susceptibleto dislodging within the treatment site. Additionally, the uniformcompression of the stent 12 about the balloon 18 substantially decreasesthe risk of the stent 12 inadvertently contacting and damaging thelining of the luminal surface of the anatomical passageway during theadvancement of the delivery catheter 14 to the desired treatment site.

Additional modifications and improvements of the present invention mayalso be apparent to those of ordinary skill in the art. Thus, theparticular combination of parts described and illustrated herein isintended to represent only one embodiment of the present invention, andis not intended to serve as limitations of alternative devices withinthe spirit and scope of the invention.

What is claimed is:
 1. An apparatus for mounting a radially expandableintraluminal stent onto a delivery catheter, said apparatus comprising:ahollow housing having an exterior and defining an interior chamberhaving a fluid port which communicates with the interior chamber; and acollapsible, resilient tubular sleeve fabricated from polyethylene,disposed within the interior chamber of the housing and sized to receivea portion of the delivery catheter having the stent positionedthereupon, said sleeve including an open end which communicates with theexterior of the housing; wherein pressurization of the interior chamberof the housing via the fluid port facilitates a uniform radialcompression of the sleeve, and a depressurization of the housing via thefluid port causing the sleeve to resiliently return to an uncompressedstate.
 2. The apparatus of claim 1 wherein the sleeve is fabricatedhaving a wall thickness of from about 0.001 to 0.003 inches.
 3. Anapparatus for mounting a radially expandable intraluminal stent onto adelivery catheter, said apparatus comprising:a hollow housing having anexterior and defining an interior chamber having a fluid port whichcommunicates with the interior chamber; and a collapsible, resilienttubular sleeve fabricated from polyethylene terephthalate, disposedwithin the interior chamber of the housing and sized to receive aportion of the delivery catheter having the stent positioned thereupon,said sleeve including an open end which communicates with the exteriorof the housing; wherein pressurization of the interior chamber of thehousing via the fluid port facilitates a uniform radial compression ofthe sleeve, and a depressurization of the housing via the fluid portcausing the sleeve to resiliently return to an uncompressed state. 4.The apparatus of claim 3 wherein said sleeve is fabricated having a wallthickness of from about 0.0001 to 0.001 inches.
 5. An apparatus formounting a radially expandable intraluminal stent onto a deliverycatheter, said apparatus comprising:a hollow housing having an exteriorand defining an interior chamber having a fluid port which communicateswith the interior chamber; and a collapsible, resilient tubular sleevefabricated from nylon, disposed within the interior chamber of thehousing and sized to receive a portion of the delivery catheter havingthe stent positioned thereupon, said sleeve including an open end whichcommunicates with the exterior of the housing; wherein pressurization ofthe interior chamber of the housing via the fluid port facilitates auniform radial compression of the sleeve, and a depressurization of thehousing via the fluid port causing the sleeve to resiliently return toan uncompressed state.
 6. The apparatus of claim 5 wherein said sleeveis fabricated having a wall thickness of from about 0.001 to 0.003inches.